\3 Biodiversity ^Heritage ^^Library http://www.biodiversitylibrary.org/ South African journal of natural history. Pretoria,South African Biological Society. http://www.biodiversitylibrary.org/bibliography/7396 v. 2 (1920): http://www.biodiversitylibrary.org/item/31375 Page(s): Page 121, Page 122, Page 123, Page 124 Contributed by: MBLWHOI Library, Woods Hole Sponsored by: MBLWHOI Library Generated 28 November 201 1 11:12PM http://www.biodiversitylibrary.org/pdf3/008808800031375 This page intentionally left blank. THE JUMPING BEAN t2L The Jumping Bean — Emporia melanobasis, Hmpsn. By A. T. Jaxse. The Jumping Bean is too well known to make it necessarv to describe the external form of the seed. It is not a beau at all, hut the schizocarp of a plant belong- ing to the Euphorbiareae. It is by no means confined m s. Africa, bnl occurs also in X. America and S. Europe, in fact it was known from Europe as early as the be- ginning of the sixteenth century, but it does not seem to have attracted as much attention then as it has done during* the last years. In 1854 a "jumping bean", re sembling in every respect The one found in South Africa. was found in Mexico and well studied by the well-known entomologist Lucas, whose observations are very con elusive. It was onlv since 1800. however, when these "beans *' were imported from Mexico in such large uian- tities, that they became more known by the public that bought them from mere curiosity. And no wonder! The jumping of these beans is a mosl weird spectacle. This peculiar movement in the seed is caused by the larva of a moth. The Mexican ''beans" develop a small moth, thai: belongs to the Tortricidae and is named bv Westw. as Oarpocapsa salfitaas. This genus has in Europe six species, all of which live inside fruit, which they all leave however before pupation, while the Mexican species pupates also inside the fruit. The jumping beans from South Africa also pupate inside the "bean", ai least the species known to me, and the one I know from the Transvaal resembles in many respects the Mexican jumping bean. The Transvaal "jumping bean M is clearly the fruit of a Euphorbiaceae, and comes from the Lvdenbunr d^'rict 122 MR. A. T. JAXSE but I have never had the opportunity of seeing more of the plant than the "beans". It seems that all the fruit are inhabited by the larvae, as a sound seetl never came to my notice nor to the notice of the collectors who sent the "beans" on to me. I also received far too little material to ask the help of a specialist to identify the plant that produces the fruit. As the generic characters of this family are founded on the structure of the seed, however, it will be impossible to identify the genus ex- cept approximately. The larvae that I found inside differed very little from other larvae that live inside plant parts, except that H was very thick in the middle probably due to abnorma 1 development of the muscular system in that region. When taken out of the "bean*', it always maintained a semi-circular position, and the size was certainly too big to allow the full grown larva to stretch itself when inside the "bean". This fact I think of great important-- in the explanation of the jumping power of the larva. When the larva came to me they were full grown and the fruit consisted of the empty shell only, yet they re mained in this larval stage from November 23rd, 1908, till June next year, when 1 found the first pupa inside those "beans" that did not jump any more. Some of them even pupated as late as October the 8th, or nearly a year after being apparently full grown. During the larval stage the "beans" jumped every now and then, often to a height of noi less than an inch, and when left by themselves in an open shallow box for some days thev would all gradually disappear. When about a hundred were confined in a cardboard box they would keep up i rattling noise, that never quite ceased, but that became more pronounced when the box was exposed to heat, r often observed that some of them kept on jumping every two or three seconds for several minutes when a shorl period of rest would be enjoyed, to begin the jumping again, especially when the temperature was rather hiffh. One naturally asks the use of this movement, but I must THE JUMPING DEAN 12*' confess, thai 1 cm n not think of any use that would justify such a considerable waste of energy, but it still, more surprises me thai the larva can keep up this move- ment Tor several months without any food, not to speak of the quantity of fund necessary to bring the young larva to maturity, not more than about twice its own volume being stored in the fruit. The fruit when sent to me weii 1 quite sound on the outer surface, not one opening or mark of en nance could he detected by me even with a magnifyer, so I presume that the larva must enter the fruit when the latter is still very young and that the larva feeds on the food brought there by tin plantparts concerned, allowing at the same time s cient food for the proper growth of the outer shell, or the moth must have a means of depositing the eggs into the tissue when the fruit is nearly full grown, but I could not find in (lie female moths that hatched out any ovipositor that even suggested its capability of performing this. Before pupation (lie larva cuts a very neat circular hole in the hardest part of the shell, without removing the centre, but this lid is only visible with the aid of a magnifyer and seems to he kept in its place from the inside by a silken surface that covers in fact the whole inside One to two months after these 1 lids are made the moths emerge and in mv beans thev all were of one species belonging to the Pyralidae family of the genus Tepkris. The species was before quite unknown to me and most probably new, but the peculiar thing is that the " jump- ing beans" of other countries contain larvae of moths be- longing to other families. The Mexican species is a Tortria?, the Transvaal species a Pyralid and the other I know from Table mountain is a Timid. This last species is described by Merrick as Scirotis a thief (t, the only speeies known of this genus. As Mr. Meyrick rightly says, these " : beans'' have nothing whatever to do. with the ^ beans " from Mexico (nor from those of Lydenburgi, as far as relationship is concerned but are more to be looked upon as special ways 121 MR. A. T. JANSE of pupation. That the Cape species has parasites need not surprise us, since the larvae live for some time outside the seed, but it is more peculiar that many of my specimens, that I have every reason to helieve to have lived nearly, if not all, their time inside the fruit, had Hymen op tenuis parasites, that bored their way through the thick shell in quite a different manner to that of the moth. I think that those Ichneumons bring their eggs intu the larvae by boring with their ovipositor into the shell in such a way that the opening is afterwards in- visible. It was not so much why the larva jumped so frequently but hoir they could perform tins feat which required such a large amount of muscular power, that puzzled me most. I partly opened several and observed it carefully, in the act of jumping, and I feel sure that the larva first contracts itself, then suddenlv stretches itself as much as space allows so as to throw, as it were, the two ends of its body against those walls of the beau that are up- wards, at the same time raising itself, and this I ^hink forces the "bean'' up for sometimes the height of an inch. Mr, Lucas made verv careful observations on the * Mexican bean, however, and comes to somewhat different conclusions. In order to observe the larva well, he took one of the tlat walls awav and placed a small niece of mica in its place. He then found that the larva climbs on to the highest wall, stretches itself till lie- ends »(' its body are at the corner of tin* bean then it contracts its body so that the larva begins to swell, then the body stretches suddenly in the direction of the upper part of the bean and this causes the bean to move in one direc- tion. 1 would not like to deride which of .the lw<> is the most probable explanation; j>erhaps there are even several means of producing (lie same thing: the uncanny niove- nirhof what is apparentlv bin a snn].